Also in Python you can use: for x in range (1,j+1): to loop j times. Although it does read as though it is looping j+1 times to those not familiar. One more comment I wanted to make about end blocks, is that a respectable editor will add them for you, together with the indentation of the next line. EditPlus 2 did it best in my experience although I think I just haven't seen a well configured alternative. I very rarely forget the block closer but I do sometimes forget the colon. Regarding the logical inconsistency of my argument, well I am saying that I would prefer my redundancy at the end of the loop rather than the beginning. To say that the status quo is better is to say that you prefer your redundancy at the beginning. Fair enough, I'm happy to respect your opinion there. I still struggle to see why it should be mandatory though? For those who prefer to have the block closing delimiters this way, is the need for a keyword (could be a command line option) really the objection? I'll have a detailed look at your colon link a bit later. On 10/01/17 09:26, Chris Barker wrote:

On Mon, Jan 9, 2017 at 5:12 PM, Simon Lovell <simon58500@bigpond.com <mailto:simon58500@bigpond.com>> wrote:

Re: Counters starting at zero vs one, Fortran has a neat solution to this for arrays if not strings - allow the programmer to select the starting index.

I liked that back in the day, but I think it's really better if it's always the same.

and see my other note for why the zero-based and open ended slicing is fabulous -- indexing really needs to match slicing.

ONe more:

since you mentioned Fortran -- it's a common use-case for an array to model some sort of regular spaced grid, so:

x = start_x + i*delta_x

really easy and logical math for figuring out where you are on a grid (and the reverse calculation) -- this is a pain with 1-based indexing....

(of course, C does this for pointer math for the same reason...)

When I've programmed for loops in C, sometimes you want zero based and sometimes one based, while most times you don't really care. To make it readable I would wherever possible write either: for (i=0;i<j;i++) for (i=1;i<=j;i++) // In both cases always executing j times

in pyton, you never right that code anyway. most of the time, it's

for item in sequence:

no indexes at all.

or:

for i in range(N): ...

indexes, but you dont care

or

for i, item in enumerate(seq): ...

or for item1, item2 in zip(sequence): ...

i.e you almost never care what the starting index is!

-CHB

Rgds

_______________________________________________ Python-ideas mailing list Python-ideas@python.org <mailto:Python-ideas@python.org> https://mail.python.org/mailman/listinfo/python-ideas <https://mail.python.org/mailman/listinfo/python-ideas> Code of Conduct: http://python.org/psf/codeofconduct/ <http://python.org/psf/codeofconduct/>

--

Christopher Barker, Ph.D. Oceanographer

Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception

Chris.Barker@noaa.gov <mailto:Chris.Barker@noaa.gov>

On Tue, Jan 10, 2017 at 12:44 PM, Simon Lovell <simon58500@bigpond.com> wrote:

Regarding the logical inconsistency of my argument, well I am saying that I would prefer my redundancy at the end of the loop rather than the beginning. To say that the status quo is better is to say that you prefer your redundancy at the beginning. Fair enough, I'm happy to respect your opinion there. I still struggle to see why it should be mandatory though? For those who prefer to have the block closing delimiters this way, is the need for a keyword (could be a command line option) really the objection?

Actually, Python does have a way to enable optional block closing directives. They're a little more compact than "endfor" and "endwhile" etc, and they're optional, so the compiler won't require you to use them (that would break heaps of libraries), but try this: -- cut -- import sys for arg in sys.argv: if arg == "hello": print("Hello, sir/madam") #if #for -- cut -- Okay, okay, that's a bit of a cheat, but still, if you really truly want "endfor", all you have to do is spell it "#for" and it'll be accepted. Don't expect experienced Python programmers to accept this at code review though. (And if you insist on a command line option, "python3 -X hashblockend" will do that for you. It won't actually DO anything though.) ChrisA

On Tue, Jan 10, 2017 at 09:44:31AM +0800, Simon Lovell wrote:

Also in Python you can use:

for x in range (1,j+1):

to loop j times. Although it does read as though it is looping j+1 times to those not familiar.

*shrug* To those "not familiar", most language features are mysterious and it is easy to guess wrong. What's the difference between foo[x+1] and foo(x+1)? In Python, the first is a key or index lookup and the second is a function call; but in Mathematica, the first is a function call and the second is foo multiplied by x+1. Python prides itself in having a much easier learning curve than many languages, with syntax that is close to "executable pseudo-code", but that doesn't mean that there is *nothing* to learn.

One more comment I wanted to make about end blocks, [...]

If I never have to see code like: end end end end end end again, it will be too soon.

I still struggle to see why it should be mandatory though? For those who prefer to have the block closing delimiters this way, is the need for a keyword (could be a command line option) really the objection?

It's not mandatory -- there are dozens of other languages you can use that will satisfy your urge for a redundant "end" block marker. But for *Python*, it is mandatory because it is Guido's language, not yours. When you design your own language, you can design it to be as complicated or simple, as baroque or plain as you like. Think about what you are asking for: a command-line option that controls whether or not the interpreter requires "end" after each block. Now every single library module needs to be written twice, once with "end", once without. Otherwise, it won't even compile for half the users. If all you care about is something physically at the end of the block, without the compiler enforcing it, then Python already supports this, using your choice of keyword: with open(filename) as f: for line in f: if condition: while something: spam(line) #end #finish #done #conclusion Problem solved. -- Steve